Sliding mode control system for internal combustion engine

Abstract

A system and method for using a sliding mode control algorithm to control flow rates from air handling actuators and fuel injectors of an internal combustion engine. The sliding mode control is based on an engine model that represents the engine in terms of pressure and oxygen content states of the intake and exhaust manifolds (as a linear term) and controllable flow rates (as a nonlinear term).

1. A sliding mode control unit for electronically controlling at least one air handling actuator of an internal combustion engine, the engine having an intake manifold and an exhaust manifold, and the engine having means for providing, during engine operation, current engine speed values, current accelerator position values, and current manifold state values, the manifold state values being intake and exhaust manifold pressure values and intake and exhaust manifold oxygen values, comprising:
 a memory for storing a map of engine speed values and accelerator pedal position values to desired air handling actuator setpoint values; 
 a memory for storing a map of engine speed values and accelerator pedal position values to desired manifold state values; 
 processing means for differencing the desired manifold state values and the current manifold state values, thereby obtaining error values; 
 processing means for using a sliding mode control algorithm to compute flow change values, based on the error values; 
 an actuator controller for computing actuator change values, based on the actuator flow change values; and 
 processing means for calculating the difference between desired air handling actuator setpoint values and the actuator change values, thereby generating actuator command values. 
 
     
     
       2. The sliding mode control unit of  claim 1 , wherein the air handling actuator is an air intake throttle. 
     
     
       3. The sliding mode control unit of  claim 1 , wherein the air handling actuator is an EGR valve. 
     
     
       4. The sliding mode control unit of  claim 1 , wherein the air handling actuator is a turbocharger output control device. 
     
     
       5. The sliding mode control unit of  claim 1 , wherein the air handing actuator is one or more of the group of: air intake throttle, EGR valve, turbocharger output device. 
     
     
       6. The sliding mode control unit of  claim 1 , wherein the sliding mode control algorithm models the engine by equating flow rate change values to a gain matrix applied to a linear term representing the error values and a nonlinear term representing a switching function. 
     
     
       7. The sliding mode control unit of  claim 6 , wherein the gain matrix is a constant matrix that represent cross coupling between flow rates and manifold states. 
     
     
       8. The sliding mode control unit of  claim 1 , wherein the sliding mode control unit is further for controlling the engine's fuel injectors and the flow rate is fuel quantity, wherein the sliding mode control algorithm further calculates a fuel quantity change value, and further comprising a fueling control process whose output is differenced with the fuel quantity change value. 
     
     
       9. A sliding mode control method for electronically controlling at least one air handling actuator of an internal combustion engine, the engine having an intake manifold and an exhaust manifold, and the engine having means for providing, during engine operation, current engine speed values, current accelerator position values, and current manifold state values, the manifold state values being intake and exhaust manifold pressure values and intake and exhaust manifold oxygen values, comprising:
 storing a map of engine speed values and accelerator pedal position values to desired air handling actuator setpoint values; 
 storing a map of engine speed values and accelerator pedal position values to desired manifold state values; 
 differencing the desired manifold state values and the current manifold state values, thereby obtaining error values; 
 using a sliding mode control algorithm to compute flow change values, based on the error values; 
 computing actuator change values, based on the actuator flow change values; and 
 calculating the difference between desired air handling actuator setpoint values and the actuator change values, thereby generating actuator command values. 
 
     
     
       10. The sliding mode control method of  claim 9 , wherein the air handling actuator is an air intake throttle. 
     
     
       11. The sliding mode control method of  claim 9 , wherein the air handling actuator is an EGR valve. 
     
     
       12. The sliding mode control method of  claim 9 , wherein the air handling actuator is a turbocharger output control device. 
     
     
       13. The sliding mode control method of  claim 9 , wherein the air handing actuator is one or more of the group of: air intake throttle, EGR valve, turbocharger output device. 
     
     
       14. The sliding mode control method of  claim 9 , wherein the sliding mode control algorithm models the engine by equating flow rate change values to a gain matrix applied to a linear term representing the error values and a nonlinear term representing a switching function. 
     
     
       15. The sliding mode control method of  claim 14 , wherein the gain matrix is a constant matrix that represent cross coupling between flow rates and manifold states. 
     
     
       16. The sliding mode control unit of  claim 1 , wherein the sliding mode control unit is further for controlling the engine's fuel injectors and the flow rate is fuel quantity, wherein the sliding mode control algorithm further calculates a fuel quantity change value, and further comprising a fueling control process whose output is differenced with the fuel quantity change value.